<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    手机号码：<input type="number">
    <button>发送</button>
    <script>
        var btn = document.querySelector('button')
        btn.addEventListener('click', function () {
            var time = 60
            btn.disabled = true
            btn.innerHTML = '还剩下' + time-- + '秒'
            var timer = setInterval(function () {
                if (time == 0) {
                    clearInterval(timer)
                    btn.disabled = false
                    btn.innerHTML = '发送'
                } else (
                    btn.innerHTML = '还剩下' + time-- + '秒'
                )
            }, 1000)
        })
    </script>
</body>
</html>